In an illuminating psychosocial inquiry into the roots of mass hatred, Kressel, who chairs the psychology department at William Paterson College of New Jersey, focuses on four examples of the eruption of murderous bigotry. In Germany, the Nazi genocide of the Jews was abetted by millions of patriotic accomplices who gave their enthusiastic support to Hitler, though aware of his willingness to launch a new war and of his hatred of Jews. In the former Yugoslavia, the drive to build a Greater Serbia--born of grandiose nationalism and memories of WWII atrocities against Serbs--in 1992 led Bosnian Serb soldiers to rape, torture and murder thousands of Muslim and Croat women. The 1993 bombing of Manhattan's World Trade Center by Muslim terrorists drew strength from a fundamentalist ideology that demonizes the West. In Rwanda in 1994, Hutu extremists slaughtered half a million Tutsi and moderate Hutu, motivated by a class-based hatred that, according to Kressel, evolved well before the arrival of colonizing Europeans. Kressel explores how powerful leaders, playing upon an us-against-them mentality, can transform law-abiding people into perpetrators of atrocities. The best bulwark against mass hate, he stresses, is a democratic political culture based on free media and human rights. (May)